feat(number): support step on faker.number.int()

Fixes faker-js#2186

src/modules/number/index.ts

@@ -67,13 +67,19 @@ export class NumberModule {
            * @default Number.MAX_SAFE_INTEGER
            */
           max?: number;
+          /**
+           * Increment value for generated number.
+           *
+           * @default 1
+           */
+          step?: number;
         } = {}
   ): number {
     if (typeof options === 'number') {
       options = { max: options };
     }
 
-    const { min = 0, max = Number.MAX_SAFE_INTEGER } = options;
+    const { min = 0, max = Number.MAX_SAFE_INTEGER, step = 1 } = options;
     const effectiveMin = Math.ceil(min);
     const effectiveMax = Math.floor(max);
 
@@ -91,11 +97,17 @@ export class NumberModule {
       throw new FakerError(`Max ${max} should be greater than min ${min}.`);
     }
 
+    if (step <= 0) {
+      throw new FakerError(`Step should be a positive number.`);
+    }
+
     const mersenne: Mersenne =
       // @ts-expect-error: access private member field
       this.faker._mersenne;
     const real = mersenne.next();
-    return Math.floor(real * (effectiveMax + 1 - effectiveMin) + effectiveMin);
+    const range = (effectiveMax - effectiveMin) / step;
+    const rand = Math.floor(real * (range + 1));
+    return effectiveMin + rand * step;
   }
 
   /**

test/number.spec.ts

@@ -163,6 +163,22 @@ describe('number', () => {
           new FakerError(`No integer value between 2.1 and 2.9 found.`)
         );
       });
+
+      it('should return a random number between min max, with a step size of 10', () => {
+        const results = Array.from(
+          new Set(
+            Array.from({ length: 50 }, () =>
+              faker.number.int({
+                min: 0,
+                max: 50,
+                step: 10,
+              })
+            )
+          )
+        ).sort();
+
+        expect(results).toEqual([0, 10, 20, 30, 40, 50]);
+      });
     });
 
     describe('float', () => {